Why is the start button doesn't work property

Hi Mola Arc,

The trigger switch that starts the saw is a common point of mechanical failure but is fortunately easy to fix. There are several YouTube videos available that show you how to take the saw apart to get to the switch; basically you just have to take the handle cover off and the switch is right there. Some videos show you taking the saw blade and protective cover off first, but others demonstrate that it's not really necessary. Here's one that looks pretty representative.

Makita Saw Repair - YouTube

That may not be the exact model of your saw, but it does show replacing the trigger. The following video shows a teardown of your specific model number, but doesn't go as far as removing the switch, but it does give you exact information on removing the handle to get to the switch.

Teardown- Makita Circular Saw 5740NB - YouTube

The switch itself seems to be readily available; here's one of the less expensive ones I ran across.

Makita 650248-0 Compatibility

I'm not suggesting you buy this (rather more expensive) one, but instead scroll down to the reviews where several of them talk about the process of replacing the switch. Read through them to get an idea of how it went for others who were replacing that same part.

Switch Sges115c-3 651288-1 - OEM Makita - eReplacementParts.com

That should get you going; it looks like a relatively simple repair on an inexpensive part, so hopefully that's all it will take to get your saw running again. Good luck, and let us know how the repair goes.

Take lots of pictures as you work and when you're done you can use them to create your own iFixit guide showing others how to perform that repair. It's easy, fun and will earn the gratitude of the iFixit community!

Create a new Guide - iFixit